Oil-fired water and air heating system



March 22, 1966 c. D. M CRACKEN 3,241,763

OIL-FIRED WATER AND AIR HEATING SYSTEM Filed Oct. 25, 1965 2 Sheets-Sheet 1 INVENTOR. 094 M .2. #4; 696467?! March 22, 1966 C. D. M CRACKEN OIL-FIRED WATER AND AIR HEATING SYSTEM Filed 001;. 25, 1963 2 Sheets-Sheet 2 United States Patent 3 241 763 @lL-FKRED WATER AND AHR rrnarnso SYSTEM Calvin D. Mac Cracken, Tenatiy, N1, assignor to Caimac Manufacturing Corporation, a corporation of New York Filed Get. 25, 1963, Ser. No. 318,861 7 Claims. (Cl. 2372) The present invention relates to an oil-fired domestic water heater and warm air central heating system which enables the use of standard sizes and types of gas water heater tanks and jackets and which is economical to install and use.

For many years there has been a well-recognized need throughout the oil industry for an oil-fired water heater which would be comparable in size and cost with a gas water heater. However, several problems as discussed below have prevented the oil industry from reaching this goal. As a result, relatively few oil-fired water heaters have been made for home use, and those which have been made have been large, bulky units and generally have cost considerably more than three times as much as gas water heaters. In view of this large price differential, the oil industry has been virtually unable to sell any water heaters to the new home market and thus, since the large majority of new homes are heated by warm air, gas water heaters have been used together with gas central heating systems.

Among the problems which have troubled the oil industry in attempts to make an economical oil-fired water heater competitive with gas are the following ones: Oil burners have not been practical for input heating rates below 100,000 Btu. per hour because nozzle apertures for high pressure burners become very small so that they tend to clog up or to give faulty spray patterns. The control and ignition system for an oil burner requires a large initial fixed cost, and a large motor is required to run the standard oil pump. Low pressure air atomizing burners, while not plagued with a small orifice, have been too expensive for serious consideration in the past.

Not counting the vaporizing burner water heaters which are virtually extinct due to maintenance problems, the relatively few oil-fired water heaters which have been built have incorporated a burner and controls similar to those used in an oil-fired home heating installation with the result that the heating rate supplied by the burner is far in excess of that actually required for suitable operation of a SO-gallon domestic water heater. Consequently, these existing oil-fired water heaters have employed a greatly over-sized burner and combustion chamber with fine passages arranged around the outside of the tank so that the over-all structure of tank plus peripheral flue passages is capable of absorbing the large quantity of heat per unit time supplied by the oil burner. This is an expensive, bulky construction and is contrasted with the compact standard 30-gallon gas water heater which uses a vertical cylindrical tank having a central flue extending up through the tank and with the gas burner located in the space under the tank.

It is an object of the present invention to provide an improved oil-fired domestic water heater and warm air central heating system.

Among the many advantages of the present invention are those resulting from the fact that it provides an oilfired domestic water heater and warm air central heating system which overcomes the problems of the prior art and enables the use of standard sizes and types of gas water heater tanks and jackets for oil-fired water heating. Moreover, the system is economical to install and use.

In accordance with the system which is described herein as an illustrative embodiment of the present invention an oil burner is used for the warm air central heating furnace and a smaller oil burner is used for the hot water heating unit. The oil pump of the central heating burner also supplies oil for the water heating burner, and solenoid valve means control the oil flow either to the furnace or to the heater or to both as may be required during operation. A small inexpensive motor, such as a shaded-pole motor drives a blower for supplying air to the small water heater burner. This burner includes a return flow bypass type of nozzle system with pressure regulator for example, such as shown in MacCracken and Wood Patents Nos. 2,590,111 and 2,590,112 and a return flow bypass nozzle for example, as shown in MacCracken Patent No. 2,567,818. A low return-line pressure and large nozzle orifice dimensions are used to provide a fuel spray rate of approximately one-third gallon per hour, thus advantageously avoiding the use of a troublesome small nozzle orifice discussed above, while providing a heat output rate in the range of a standard 30-gallon to 40-gallon gas heater. By virtue of this low heat output rate a standard type of gas heater tank and jacket are used with attendant economies resulting from existing very high volume mass production of these tanks and jackets. The heater burner includes a first combustion chamber contiguous with the region just below the lower end of the tank so that substantially all of the burning occurs within this first combustion chamber. This burner is of the high velocity complete combustion type producing a clean flame without soot deposition. The heated gases from this burner enter the region beneath the tank and then pass up the central flue so as to heat the water. Advantageously, somewhat higher heat output rates and efliciencies are achieved on the same water heater tank by actual test with the oil burner as shown and described as compared with a conventional gas fired burner, because there are greater radiant heating properties in the oil flame. Also, there are higher combustion gas velocities adjacent to the heat exchange surfaces as provided by the high-velocity, blower-powered oil burner shown and described herein which enhances the heat exchange action, as compared with the natural draft operation of a conventional gasfired burner. In addition, higher flame temperatures are obtained by this forced-draft oil burner as compared with the conventional natural draft gas burner. A doublepole, double-throw water heater thermostat turns on the furnace motor to drive the oil pump whenever the water is to be heated, regardless of whether the room thermostat is calling for heat from the furnace.

The conventional oil pump of the central heating burner has plenty of capacity for supplying the oil-fired burner of the water heater as well as the oil burner of the furnace itself. Conventional high-pressure oil pumps have a capacity of approximately 16 gallons per hour when new and after prolonged usage and wear this may be reduced to approximately 10 to 12 gallons per hour. T-hese pumps require about 45 watts of driving power. However, domestic oil burners have a usage rate in the range from 0.75 up to 2 gallons per hour, with the most numerous ones being near the lower end of this range. The reason why the conventional oil pump has such an excess capacity and has been of this excess capacity for many, many years, is that the pump is desired to be able to prime the oil line from the tank within the normal stackswi-tch delay time of about seconds. The pump must draw the air out of the line when the system is first turned on or whenever the tank has been refilled after being emptied. It is desired to prime this line in only one or two starting cycles of 90 seconds. Added reasons are that these pumps are mass produced and have several applications; whereas a smaller pump is not much cheaper to make or operate and is not so widely applicable. the pump can easily supply the oil for both burners.

In this specification and in the accompanying drawings is described and shown an oil-fired domestic water heater and warm air central heating system embodying the invention, and it is to be understood that this disclosure is not intended to be exhaustive nor limiting of the invention, but is set forth for purposes of illustration in order that others skilled in the art may fully understand the invention and the manner of its application in practical use.

The various objects, aspects, and advantages of the present invention will be in part pointed out and in pait apparent from the following description of an illustrative embodiment of this invention when considered in conjunction with the accompanying drawings, in which:

FIGURE 1 is a front elevational view of an oil-fired domestic water heater and warm air central heating furnace;

FIGURE 2 is a top plan view of the oil-fired water heater unit as shown in FIGURE 1;

FIGURE 3 is a sectional view of the lower portion of the water heater tank and burner as seen along the line 33 of FIGURE 1; and

FIGURE 4 is a schematic circuit diagram of the electrical controls for this system.

As shown in the drawings, a system embodying this invention includes a warm air furnace (FIGURE 1) which is arranged to circulate heated air to the various rooms in a home through ducts as in a conventional central warm air home heating installation. A room thermostat 12 is located in a suitable position such as in a hallway or living room and serves to control the furnace 10 to maintain the living quarters at the desired temperature. An oil burner 14 of conventional type together with its associated equipment provides the heat for the furnace 10. This oil burner 14 includes a relatively large motor 16, for example such as a capacitor start induction motor, with a centrifugal blower 18 and a high-pressure oil pump 20 driven by the motor shaft. The pump 20 is capable of delivering oil at a pressure in excess of 100 pounds per square inch for use by an oil spray nozzle, and the oil is drawn from a storage tank (not shown) through a main line 22 extending to the pump 20. For feeding the oil to the burner 14 a high-pressure supply line 24 is connected to the discharge of the pump, and a solenoid valve 26 controls the admission of the high pressure oil from the supply line 24 into the burner. An ignition transformer 28 energizes electrodes within the burner for igniting the oil.

In order to control the operation of the furnace 10 there is a stack relay 30 which is responsive to the temperature of the flue gases issuing from the furnace through an exhaust duct 32, which is connected to a chimney or other suitable flue for discharging the combustion products outside of the home. The stack relay 30 operates to shut off the oil burner 14 in the event that the burner fails to ignite when the room thermostat 12 has turned the burner on or in the event that the burner should become extinguished for any reason during a period when the burner is turned on. A fan and limit control thermostat 34 responds to the temperature of the heated air being supplied by the furnace and serves to control the operation of the circulating blower (not shown) which moves the warm air to the living quarters in the home. Also, this fan and limit control 34 shuts off the burner 14 if for any reason the temperature of the air being heated should rise above a preset limit. The room thermostat 12, stack relay 30, and fan and limit control 34 are connected through respective electrical cables 36, 38 and 40 into a main junction box 42 which is connected to the burner 14 through an electrical cable 44.

The furnace 10, oil burner 14 and electrical control system as described above include conventional components as will be understood and the details and operation there- Thus,

of are described hereinafter insofar as they relate to the present invention.

As shown in FIGURES 1, 2 and 3 the oil-fired water heater unit 50 includes a cylindrical water tank 52 having an axial flue duct 54, for example such as a 30 gallon tank of the type used in conventional gas water heaters. A layer of insulation 56 (FIGURE 3) surrounds the tank and is housed in a metal jacket 58 including legs 60. This insulation 56 and the jacket 58 are of standard construction as used in a 30 gallon gas water heater, except that there is a circular side port 61 for admit-ting the discharge end or mouth of a compact oil burner. The upper end of the central flue passage 54 is connected through an exhaust duct 62 leading to a chimney flue or other suitable exhaust from the home.

As shown most clearly in FIGURE 3, the lower end 64 of the tank 52 has a concave configuration so as to withstand the internal pressure and to provide a funnellike dome for guiding into the passage 54 the hot gases from a chamber 66 beneath the tank 52. Also, this concave tank end 64 provides a heat-exchange surface for absorbing heat from the chamber 66 which is surrounded by the lower portion of the jacket 58 and also by the insulation layer 56 with a metal lining 68 defining the chamber 66.

In a conventional gas water heater the gas burner is usually located within this chamber 66.

In the oil-fired water heater system as shown a small oil burner 70 is connected to one side of the jacket 58 and includes a housing 72 with a removable cover plate 74. A centrifugal blower 76 driven by a small inexpensive motor, for example such as a shaded-pole motor supplies air into the burner housing 72 at a pressure of approximately three inches of water. Within the housing 72 is a high velocity complete combustion burner structure 78, for example such as the burner structure shown in MacCracken Patent No. 2,692,014 or a double vortex burner structure as made by Combustion Research Company, Studio City, California. This high velocity burner structure 78 produces a flame within itself extending from its outer end 80 to a point just slightly within the tank chamber 66. The tip end of the clean flame 84 is illustrated in FIGURES 2 and 3 extending a short distance beyond the mouth 82 of the burner structure 78. By virtue of this arrangement the oil flame burns cleanly and does not deposit soot within the central flue passage 54. Moreover, the flame 84 is spaced away from the lower end of the tank 52 so as to prevent overheating, thus maintaining a reasonably long service life for the tank 52. The burner structure 78 is prevented from overheating because it is surrounded by the inrushing air from the blower 76, and this inrushing air passes into the burner structure 78 through a multitude of small openings 86 (FIGURES 2 and 3). Thus, the burner structure 78 is washed in a bath of inrushing cool air, and the intense flame 84 therein is prevented from coming in contact with the burner structure 78 by the continuous entry of air through the multiple orifies 86.

In order to supply a spray of oil into the burner structure 78, there is a return flow by-pass type of nozzle 88 directed down into the burner structure 78. The highpressure oil supply line 24 has an extension 90 connected from the furnace 10 over to the nozzle 88, with a solenoid valve 92 in the line 90 near the water heater 50. There is a return flow of oil from the nozzle 88 back through a return line 94 to the pump 20, and a pressure regulator 96 controls the flow of oil from the nozzle 88 back through the line 94, thus controlling the effective rate of oil discharge from the large orifice of the nozzle 88. An example of a suitable structure for this return flow by-pass nozzle 88 is shown in Patent No. 2,567,818, and examples of suitable return-flow systems including pressure regulators are shown in Patents Nos. 2,590,111 and 2,590,112. Thus, the nozzle 88 has an orifice diameter of practical size to avoid clogging problems and to give a symmetrical stable spray pattern and yet is capable of supplying oil at a very low delivery rate in the range from A1 to /2 gallons per hour. In this illustrative system the oil delivery rate is set at approximately /3 gallon per hour, but it may be varied within this range by adjusting the pressure regulator 96.

The oil in the burner structure '78 is ignited by the spark from a pair of electrodes 98 which are energized from an ignition transformer 100. A water thermostat 102 (FIGURE 4), a flame sensor 104 and an electrically heated bi-metal time-delay switch 106 are all contained in a control box 108 and serve to control the operation of the water heater burner 70 as will be explained in connection with FIGURE 4.

As shown in FIGURE 4 the water thermostat 102 includes a double-pole double-throw switch having a ganged pair of contact arms 110 and 112. During operation of this system when the temperature of the water in the tank 52 has fallen sufiiciently low to call for heating of the water, then these contact arms 110 and 112 both swing into their colt position, as indicated. In this cold position of the water thermostat, the furnace blower and oil-pump motor 16 is directly energized by connection to a pair of main electrical lines L and L Thus, the motor 16 is running to provide oil pressure in the supply line 90 to the water heater (FIGURE 1), regardless of whether or not the furnace controls 12, 30 and 34 are calling for operation of the furnace oil burner 14. However, if the furnace controls 12, 30 and 34 do also happen to call for operation of the oil burner 14, then the motor 16 is running as required. The circuit for energizing the motor 16, when the water thermostat 102 is in the cold position, is traced from the main line L through a connection 114 to a contact A which is engaged by the arm 112, and this circuit continues through this arm 112 and through a connection 116 to one side of the motor 16 and then through a connection 110 to the other line L In this system the lines L and L are supplying alternating current at suitable voltage and frequency, for example, 120 volt 60 cycle AC. The line L is shown as being the hot line, while the line L is the return line which is grounded so as to be at ground potential in the electrical system of the home.

The electrical line L is connected to the switch arm 110 in the water thermostat 102. Assuming that this thermostat 102 is in its cold position, then this contact arm 110 is in engagement with a contact C which is connected through a water heater control lead 120 extending to the ignition transformer 100 and to the blower motor 76. The respective opposite sides of the transformer 100 and of the motor 76 are connected to the return line L Thus, whenever the common connection 120 is energized through the switch arm 110, then the blower motor '76 and ignition transformer 100 are placed in operation.

In order to operate the solenoid valve 92 for controlling the oil spray into the Water heater burner 70, the water heater control connection 120 extends to a warp switch 106. This circuit for controlling the solenoid valve 92 passes through the warp switch 106 to a flame sensor switch 104- and from the opposite side of this sensor switch to a lead 122 connected to one side of the solenoid oil valve 92, with the opposite side of this valve 92 being connected to the return line L Thus, the solenoid valve 92 is opened to supply oil to the burner 70 only when the warp switch 106 is closed.

The warp switch 106 is an electrically heated bi-metalactuated time-delay switch which has a normally closed contact member 124. An electrical resistance heating element 126 is in series with the solenoid valve 92 and is positioned in heat transfer relationship with respect to the bi-metal element in the warp switch 106. This resistance element 126 conducts sufficient current when the warp switch 106 is closed so as to open the valve 92. In operation the heating effect from this resistance element 126 causes the contact arm 124 to snap into its open position after an appropriate time-delay period so as to shut off the solenoid valve 92. After this warp switch contact arm 124- has snapped open it remains open until it is reset into its closed position by manually pressing a reset button 128.

The flame sensor switch 104 is normally open when it is cool, and it is in heat exchange relationship with the water heater chamber 66 (FIGURE 3) so that it rapidly heats up and becomes closed when the burner 70 is operating properly. This flame sensor switch 104 is in shunt with the resistance heating element 126. Consequently, if the burner 70 ignites properly during the first few moments after the water thermostat 102 calls for heating, then the sensor switch 104 soon closes, and upon its closure the resistance heating element 126 is effectively short-circuited before the warp switch 106 has become sufficiently hot to snap open.

However, if the water heater burner 70 fails to ignite or if it becomes extinguished for any appreciable period, then the sensor switch 104 opens so as to place the resistance heater 126 in operation. After an appropriate time-delay period the warp switch contact arm 124 snaps open to shout off the oil valve 92.

When the water has reached the desired heated temperature, the contact arms 110 and 112 of the water thermostat 102 swing up to their hot position. In this position the motor 16 is connected in parallel with the furnace solenoid oil valve 26 and with the furnace ignition transformer 28 so that the motor 16 is now controlled by the furnace controls 12, 30 and 34 in the same manner as the valve 26 and ignition transformer 28. These furnace controls 12, 30 and 34 comprise the room thermostat 12, stack relay 30, and fan and limit control 34 as shown in FIGURE 1. The circuit for energizing the motor 16 when the water thermostat 102 is in the hot position is traced from the line L through the controls 12, 30 and 34 to a common connection 130 which extends to a contact B which is now engaged by the contact arm 112 and thence to the motor lead 116.

When the water thermostat 102 is in its hot position the other contact arm 110 engages an open-circuit con tact D so that the water heater control line is deenergized.

It is to be noted that all of the components physically associated with or in close proximity with the water heater 50 or with the oil burner 14 are shown in FIG- URE 4 as being on respective sides of the dashed reference line 132 for illustrating the advantageous interrelationship of the various components. This oil-fired system advantageously requires only four electrical connections between the water heater 50 and the furnace oil burner 14-; these four connections being the leads 116 and in addition to the electrical supply lines L and L The purpose of these two connections 116 and 130 as eX- plained above is to operate the pump motor 16 whenever the Water thermostat calls for heat regardless of whether or not the ftunace controls 12, 30 and 34 happens to be calling for operation of the furnace burner 14.

The illustrative embodiment of the invention described above includes an oil-fired domestic water heater, and it is to be noted that the fuel piping, burner and control system is adapted for use in various types of oilfired heating appliances other than water heaters. For example, this invention is adapted for use in oil-fired appliances such as incinerators, clothes dryers, heat-operated air conditioners, barn heaters, agricultural heaters, and swimming pool heaters and in systems including a plurality of such appliances. An oil-fired incinerator embodying this invention is well suited for use in rural, farm and summer homes in locations wherein refuse collections are not available.

From the foregoing it will be understood that the oil-fired domestic water heater and warm air central heating system described herein as an illustrative embodiment of the present invention is well suited to provide the advantages set forth and that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense and that in certain instances some of the features of the invention may be used without a corresponding use of other features or may be modified into equivalent elements, all without departing from the scope of the invention as defined by the following claims.

What is claimed is:

1. An oil-fired domestic water heater system comprising a water heater tank having a heating chamber at the bottom with a central flue extending up from said chamber through the tank for passage of combustion product gases therethrough, said chamber having an opening at one side, a first oil burner including a selfcontained combustion zone outside of said chamber with a combustion discharge end of said burner directed into said chamber through said side opening, a small motor blower for supplying air to said first burner, an ignition circuit for said burner, a first solenoid valve, a nozzle connected to said valve and directed into said combustion zone for supplying oil spray to said zone, a water thermostat responsive to the temperature of the water in said tank, first circuit means connecting said water theranostat to said small motor blower, to said ignition circuit and to said solenoid valve for controlling said small motor blower, said ignition circuit and said solenoid valve, a second oil burner for a central heating furnace, said second burner having a high-pressure oil pump, a second blower, a second motor for driving said second blower and said oil pump, a connection from said oil pump to said first solenoid valve for supplying oil to said first solenoid valve, a second solenoid valve connected to said oil pump for controlling the flow of oil to said second oil burner, and second circuit means for connecting said water thermostat to said second motor for operating said second motor to operate said high-pressure oil pump when said water thermostat calls for heating of the water, regardless of whether said second burner is operating.

2. An oil-fired domestic water heater system comprising a water heater tank having a heating chamber at the bottom with a central flue extending up from said chamber through the tank for passage of combustion product gases therethrough, a first oil burner communicating with said chamber for supplying hot combustion product gases thereto, a first blower for supplying air to said first burner, a shaded-pole motor for driving said blower, an ignition circuit for said burner, a high pressure oil supply line, a first solenoid valve connected to said line, a nozzle connected to said valve and directed into said first burner for supplying oil spray to said first burner, a water thermostat responsive to the temperature of the water in said tank, said water thermostat including first switch means and second switch means, first circuit means connecting said first switch means to said shaded-pole blower motor, to said ignition circuit and to said solenoid valve for controlling said shaded-pole blower motor, said ignition circuit and said solenoid valve, a second oil burner for a central heating furnace having a high-pressure oil pump, a second blower, and a second motor for driving said second blower and oil pump, a connection from said oil pump to said high pressure supply line, second circuit means connecting said second switch means in said water thermostat to said second motor for operating said second motor to drive said high-pressure oil pump when said water thermostat calls for heating of the water, regardless of whether said second burner is operating.

3. An oil-fired domestic water heater and warm air central heating oil burner system comprising a water heater tank having a heating chamber at the bottom with a central flue extending up from said chamber through the tank for passage of hot combustion product gases therethrough, said chamber having an inlet at one side, a first oil burner including a flame container having a plurality of openings therein, said flame container having a flame discharge mouth directed through said inlet into said chamber, a housing surrounding said flame container, a first blower for supplying air into said housing and through said openings into said flame container for supporting combustion therein, a first electric motor for driving said first blower, an ignition circuit for said first burner, a first electrically operated oil valve, a nozzle connected to said valve and directed into said flame container for supplying oil spray to said container, an A.C. supply line, a water thermostat responsive to the temperature of the water in said tank, said water thermostat including first and second switch means each having hot and cold operating positions, said first switch means in its cold position connecting said A.C. supply line to said first motor, to said ignition circuit and to said first oil valve, and said first switch means in its hot position disconnecting said A.C. supply line from said first motor, ignition circuit and first oil valve, a second oil burner for a warm air central heating furnace, said second burner having a high-pressure oil pump and a second motor for driving said oil pump, connection means for connecting said oil pump to said first oil valve, a second electrically operated oil valve connected to said oil pump for controlling the fiow of oil from said pump to said second oil burner, a second ignition circuit for said second burner, and furnace control means for controlling said second burner, said furnace control means being connected to said second valve and to said second ignition circuit, said second switch means in its cold position connecting said A.C. supply line to said second motor for driving said pump and in its hot position connecting said second motor to said furnace control means for operating said second motor thereby.

4-. An oil-fired domestic water heater system comprising a water heater tank having a heating chamber at the bottom with a central flue extending up from said chamber through the tank for passage of combustion product gases therethrough, said chamber having an opening at one side, a first oil burner including a self-contained combustion zone outside of said chamber with a combustion discharge end of said burner directed into said chamber through said side opening, a blower for supplying air to said first burner, a small motor for driving said blower, an ignition circuit for said first burner, an electrically operated oil valve, a nozzle connected to said valve and directed into said combustion zone for supplying oil spray to said zone, a water thermostat responsive to the temperature of the water in said tank, first circuit means connecting said water thermostat to said small motor, to said ignition circuit and to said oil valve for controlling said small motor, said ignition circuit and said electrically operated oil valve, flame sensor control means in circuit with said oil valve for shutting off said oil valve in the event said first burner fails to ignite or becomes extinguished, a second oil burner for a central heating furnace, said second burner having a high-pressure oil pump and a pump motor for driving said oil pump, connection means for making a connection from said oil pump to said electrically operated oil valve, and second circuit means for connecting said water thermostat to said pump motor for operating said pump motor when said water thermostat calls for heating of the water, regardless of whether said second burner is operating.

5. An oil-fired hot water heater and furnace system comprising a water heater including a tank for holding water to be heated, a first oil burner for said Water heater for heating the Water in said tank, a first electrically operated oil valve, a nozzle connected to said first valve and directed into said first burner for supplying oil spray to said first burner, a water thermostat responsive to the temperature of the Water in said tank, a second oil burner for a central heating furnace, said second burner having a high-pressure oil pump and a pump motor for driving said oil pump, connection means for connecting said oil pump to said first oil valve, a second electrically operated oil valve connected to said oil pump for controlling the fiow of oil from said pump to said second oil burner, circuit means connecting said water thermostat to control the energization of said first valve and said pump motor for controlling said first valve and said pump motor in response to the temperature of the water in said tank, and control means responsive to the temperature of the furnace for controlling the operation of said second burner, said second valve and said pump motor in response to the temperature of said furnace.

6. An oil-fired domestic water heater and warm air central heating oil burner system comprising a water heater tank having a heating chamber at the bottom with flue means extending up from said chamber in heat exchange relationship with the tank for passage of hot combustion product gases therethrough, a first oil burner in communication with said chamber, a blower for supplying air to said first burner for supporting combustion therein, a first electric motor for driving said blower, an ignition circuit for said burner, an electrically operated oil valve, a normally-closed time-delay switch in circuit in series with said valve, said time-delay switch having an electric heater and being opened by action of said heater after passage of the delay period, a normally-open heatsensing switch in heat sensing relationship with said burner and being closed by the heat of combustion in said first burner, said heat-sensing switch in said series circuit and also being in shunt with said heater, a nozzle in said first burner connected to said valve for supplying oil spray to said first burner, an alternating current AC. supply line, a water thermostat responsive to the temperature of the water in said tank, said water thermostat including first and second thermostat switch means each having hot and cold operating conditions, said first thermostat switch means in its cold condition connecting said A.C. supply line to energize said first motor, to said ignition circuit and to said series circuit, and said first thermostat switch means in its hot condition disconnecting said A.C. supply line therefrom, a second oil burner for a warm air central heating furnace, said second burner having a high-pressure oil pump and a second motor for driving said oil pump, connection means for connecting said oil pump to said oil valve, a second electrically operated oil valve connected to said oil pump for controlling the flow of oil from said pump to said second oil burner, furnace control means for said second burner, said second thermostat switch means in its cold condition connecting said second motor to said A.C. line and in its hot condition connecting said second motor to said furnace control means for operating said pump whenever said water thermostat is in its cold condition and whenever said furnace control means calls for heat.

7. An oil fired domestic water heater system comprising a heater tank for holding water to be heated and having a heating chamber at the bottom with a central flue extending up from said chamber through the tank for passage of combustion product gases therethrough, a first oil burner for supplying combustion product gases into said heating chamber, a blower for supplying air to said first burner, a small motor for driving said blower, an ignition circuit for said first burner, an electrically operated oil valve for said first burner, a nozzle in said first burner connected to said valve for supplying oil spray to said first burner, a water thermostat responsive to the temperature of the water in said tank, first circuit means connecting said water thermostat to said small motor, to said ignition circuit and to said oil valve for controlling said small motor, said ignition circuit and said valve, flame sensor control means in circuit with said oil valve for shutting off said oil valve in the event said first burner fails to ignite or become extinguished, a second oil burner for a central heating furnace, said second burner having a high-pressure oil pump and a pump motor for driving said oil pump, connection means for making a connection from said oil pump to said oil valve for said first burner for supplying oil to said first burner, and second circuit means for connecting said water thermostat to said pump motor for operating said pump motor when said water thermostat calls for heating of the water, regardless of whether said second burner is operating.

References Cited by the Examiner UNITED STATES PATENTS 1,493,919 5/1924 Cunningham 237-2 1,730,829 10/1929 Shivers 158-28 1,884,256 10/1932 Rogers et al 237-8 X 2,353,146 7/1944 Chea'sley 2-37- 2 2,358,809 9/1944 Jennings 237-8 2,590,111 3/1952 MacCracken 15836.3

EDWARD MICHAEL, Primary Examiner, 

1. AN OIL-FIRED DOMESTIC WATER HEATER SYSTEM COMPRISING A WATER HEATER TANK HAVING A HEATING CHAMBER AT THE BOTTOM WITH A CENTRAL EXTENDING UP FROM SAID CHAMBER THROUGH THE TANK FOR PASSAGE OF COMBUSTION PRODUCT GASES THERETHROUGH, SAID CHAMBER HAVING AN OPENING AT ONE SIDE, A FIRST OIL BURNER INCLUDING A SELFCONTAINED COMBUSTION ZONE OUTSIDE OF SAID CHAMBER WITH A COMBUSTION DISCHARGE END OF SAID BURNER DIRECTED INTO SAID CHAMBER THROUGH SAID SIDE OPENING, A SMALL MOTOR BLOWER FOR SUPPLYING AIR TO SAID FIRST BURNER, AN IGNITION CIRCUIT FOR SAID BURNER, A FIRST SOLENOID VALVE, A NOZZLE CONNECTED TO SAID VALVE AND DIRECTED INTO SAID COMBUSTION ZONE FOR SUPPLYING OIL SPRAY TO SAID ZONE, A WATER THERMOSTAT RESPONSIVE TO THE TEMPERATURE OF THE WATER IN SAID TANK, FIRST CIRCUIT MEANS CONNECTING SAID WATER THERMOSTAT TO SAID SMALL MOTOR BLOWER, TO SAID IGNITION CIRCUIT AND TO SAID SOLENOID VALVE FOR CONTROLLING SAID SMALL MOTOR BLOWER, SAID IGNITION CIRCUIT AND SAID SOLENOID VALVE, A SECOND OIL BURNER FOR A CENTRAL HEATING FURNACE, SAID SECOND BURNER HAVING A HIGH-PRESSURE OIL PUMP, A SECOND BLOWER, A SECOND MOTOR FOR DRIVING SAID SECOND BLOWER AND SAID OIL PUMP, A CONNECTION FROM SAID OIL PUMP TO SAID FIRST SOLENOID VALVE FOR SUPPLYING OIL TO SAID FIRST SOLENOID VALVE, A SECOND SOLENOID VALVE CONNECTED TO SAID OIL PUMP FOR CONTROLLING THE FLOW OF OIL TO SAID SECOND OIL BURNER, AND SECOND CIRCUIT MEANS FOR CONNECTING SAID WATER THERMOSTAT TO SAID SECOND MOTOR FOR OPERATING SAID SECOND MOTOR TO OPERATE SAID HIGH-PRESSURE OIL PUMP WHEN SAID WATER THERMOSTAT CALLS FOR HEATING OF THE WATER, REGARDLESS OF WHETHER SAID SECOND BURNER IS OPERATING. 